     (fn [game group]
       (let [ world (.world game)
              pos (.position group)
-             possible-destinations (filter #(pos-free? game %) (land-cells-around world pos migration-radius))]
+             possible-destinations (filter #(pos-free? game %) (land-cells-around world pos (migration-radius group)))]
         (if (empty? possible-destinations)
           0.0
           (let [p (prosperity-in-pos game group pos)

            pop (-> tribe .population total-persons)
            world (.world game)
            pos (.position tribe)
            possible-destinations (filter #(pos-free? game %) (land-cells-around world pos migration-radius))]
        (if
          (and (> pop 35) (< c 0.9) (not (empty? possible-destinations)))
          (/ (opposite c) 2.7)

      (let [ world (.world game)
             pos (.position group)
             _ (check-valid-position world pos)
             possible-destinations (filter #(pos-free? game %) (land-cells-around world pos (migration-radius group)))
             preferences (map (fn [pos] {
                                     :preference (perturbate-low (prosperity-in-pos game group pos))
                                     :pos pos
